Building area is the footprint of a building measured to the inside face of the exterior walls, including enclosed spaces and deductions for mechanical shafts, vertical circulation, and other factors. In some markets, records are pulled from architectural drawings by the developer and submitted to the city before the property is built. This measurement is often considered a “walls out” measurement, meaning the footage includes all of the space to the exterior wall.
The finished square footage of each level is the sum of the finished areas on that level measured at floor level to the exterior finished surface of the outside wall or to the center-line of a dividing wall. If you’re selling a condo in a multi-family unit, you would only measure square footage from interior wall to interior. Storage space has an Occupant Load Factor of 300, so it would at most have four people in it (rounded up). Assembly spaces like conference rooms might have an Occupant Load Factor of.
The ANSI method specifies measuring from the exterior of the house, but wall width is not usually subtracted to account for actual living space. Stairways and closet areas are included in the house’s size. Building size based on the outside face of the walls is a good baseline, and it’s easy to fix earlier in the project.
Chapter 3 provides the criteria by which buildings and structures are classified into use groups and occupancies. The floor area of a building, or portion thereof, not provided with surrounding exterior walls shall be the usable area under the horizontal. In Groups H-2 and H-3, not less than 25% of the perimeter wall of the occupancy shall be an exterior wall.
Building gross square footage is usually the area of construction to the outside face of the exterior walls. Covered areas like porches, covered areas, and covered areas should be located within 15 feet of the end of each wall and at intervals not exceeding 30 feet measured horizontally along the wall or partition.
📹 AC 022 – Egress: How to calculate occupant loads (Part 2 of 2) – Gross vs. Net. Sq. Ft
This video describes the basic differences between Gross and Net square feet when trying to obtain occupant loads per the IBC.
Do you include exterior walls in square footage?
Square footage of a home is calculated from the outside dimensions of the structure, including exterior and interior wall thickness. To calculate, use a 100-foot tape measure and walk around the exterior, measuring each segment and drawing the shape. If the exterior has square corners, take measurements at the foundation and round to the nearest half foot. If overhangs or slopes make exterior measurements difficult, measure from the inside and add the width of each exterior wall. Break the shape into a series of rectangles and use simple math to calculate the square footage.
Are exterior walls included in rentable square footage?
Usable Square Footage (USF) is the total floor area within a space or building that can be effectively utilized, measured from the outer surface of exterior walls and windows, including the midpoints of interior walls adjoining other spaces, hallways, or common areas. It differs from Rentable Square Footage (RSF), which determines the area for which rent is paid. Interior wall measurements are often used by architects and tenants, which may yield a smaller figure than the landlord’s calculation of USF or RSF.
Accurate measurement of USF requires understanding measurement locations and wall thickness. Architects or space planners are better equipped to provide precise measurements compared to individuals using tape measures or lasers. Comparing field measurements with verified CAD documents can further reduce potential errors. USF should exclude common areas within a building, such as public corridors, hallways, and restrooms.
Does floor area include walls?
Gross floor area (GFA) in real estate refers to the total floor area inside a building, including external walls and roof. Definitions vary globally, and some developers use GFA and gross leasable area (GLA) interchangeably, excluding public areas like corridors and corridors. Hong Kong law Chapter 123F, Building (Planning) Regulations, Regulation 23 sect 3 sub-paragraph (a) defines GFA as GLA.
Does gross sf include exterior walls?
The term “building floor area” is defined as all areas on all floors, including vertical penetration areas for circulation and shaft areas connecting floors, within the exterior faces of the walls.
How do you calculate building occupancy?
To calculate the occupant load for a building, classify each space into code prescriptive categories, calculate its area, determine the occupant load factor for each category, divide the total area by the occupant load factor, and add the total occupants for each space to get the total occupants for the entire building. This information can be used to design features like egress components, door hardware, and plumbing fixtures. If you need assistance with calculating the occupant load, consult licensed architects or engineers.
What parts of a building are not included in the floor area?
The gross floor area of a building is calculated from the exterior faces of exterior walls or the centerline of walls separating buildings, excluding covered walkways, open roofed-over areas, porches, pipe trenches, exterior terraces or steps, chimneys, roof overhangs, and similar features. It is unclear if the area of emergency stairs (from basements to the top level) should be included in the calculation.
What is the formula of occupancy?
The occupancy rate is a measure of a hotel’s capacity, calculated by dividing the number of occupied rooms by the total number of rooms and multiplying by 100. In a scenario where 15 rooms were booked, the occupancy rate would be 30. This indicates potential growth areas, as the number of unoccupied rooms exceeded the occupied ones. It’s important to distinguish between the occupancy rate and the vacancy rate, which are distinct metrics with different insights. The vacancy rate is determined by multiplying the number of unoccupied rooms by 100 and dividing by the total room count.
Are exterior walls considered structural?
External walls are load-bearing as they support the roof and upper stories of a building and may also bear weight from external elements like snow or wind. They may contain important structural elements like beams or columns that need to be considered when planning a renovation project. Partial walls, such as half or knee walls, may also be load-bearing, separating spaces while maintaining an open feel.
Identifying any structural elements within partial walls is crucial before removing or altering them. To determine if an interior column or post is load-bearing, look at the building’s blueprints or use tricks to determine if the post bears a load.
How do you calculate property occupancy?
The physical occupancy rate is the percentage of available rental space occupied with paying tenants, calculated by dividing the number of units rented by the number available to be rented. For example, if you have 50 units available for renting and 45 have paying tenants, the physical occupancy rate is 90 percent.
The leased occupancy rate is calculated by dividing the current number of units occupied by the number of units with signed leases yet to move in, dividing by 100. This measurement can be misleading, as it may not accurately reflect the occupancy of all units.
The economic occupancy rate is the proportion of gross potential rent collected, which is the money actually paid to your business. To calculate the economic occupancy rate, apartment building owners multiply the number of apartments by the amount of rent that could be charged for each unit, deducting any rent not received due to vacant or free-to-rent units, and the amount of discounts given. For example, if one apartment is vacant and another is discounted, the economic occupancy rate is 96. 4 percent.
Does outdoor space count as square footage?
In order to obtain an accurate measurement of the square footage of a house, it is essential to focus on the exterior footprint, including both heated and cooled living space. It is important to exclude garages, decks, patios, and porches from the measurement in order to obtain an accurate representation of the total living space.
What is not included in floor area?
The floor area ratio is a measure of a building’s floor area, not just its footprint. It excludes unoccupied areas like basements, parking garages, stairs, and elevator shafts from the square footage calculation. Buildings with different stories can have the same floor area ratio value, but cities have a safe load factor, which limits the safe use of space. The floor area ratio is variable due to population dynamics, growth patterns, construction activities, and the land or space where a building is placed. Industrial, residential, commercial, agricultural, and nonagricultural spaces typically have different floor area ratios.
📹 How the Maximum Occupancy of a Building is Calculated
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first off thank you for the articles. Ive been practicign for 30 years and still will come back to your articles for certain projects.Great job with your narration and illustrations! Each jurisditction can treat occupant load calc different but one point I have tried to argue in the past is that in assembly spaces, you should be able to deduct casework like kitchen counters and appliaces as the net. Agree?
Your delivery is so on-point, current (not an old gray haired dude like myself relaying the info) and engaging (modern graphics instead of the static PowerPoint snoozers). As a plans reviewer, It is so difficult to get our customers to understand occupancy calcs in general and the differnces in Gross and Net in particular. These articles are going to go a long way in helping us relay this information. Great job and new sub here.
Excellent stuff! I think your next article should be a quick, run down on the permitting process, since you have the articles just a run down of the bullet points, occupancy type and load, building types, fire separation, means of egress, and system integration! Thanks for all the articles you do! We watch them in the office all the time !
How to you handle the occupant load for a facility where the overall occupant load factor is net? For example, a daycare use is 35net. If the only other spaces in your daycare building are mech/elect/I.T. rooms, small storage under 100sf, and toilet rooms, do you calculate the occupant load of the daycare spaces at 35net and exclude everything else? Or do you have to calculate and occupant load for the rest of excluded spaces in the building – 300sf for mech/elec/I.T./storage, and what for the toilet rooms?
I’m a fairly new fire inspector and have been tasked with determining the OL for a portion of our city council chambers. The room is a large room that is divided in half by a 3ft high wall. City council members have their desks and chairs on one side of the 3ft wall while the other side of the 3ft wall contains chairs for members of the public to sit and view the meetings. They want to know how many members of the public are permitted in that portion. The “public” half a perfect square floor plan with rows of chairs side by side. Am I correct in thinking that I just measure the SF of that half of the area and use “chairs only” and “standing room” factors to get the OLs for seated and standing? Thanks
I’m still confused about gross. Does this include balconies? Moreover, outdoor open ground floor space over a transfer slab? I say this because i believe gross does include this per ibc, but it feels strange to include outdoor area beyond an exit discharge. I see you referenced chapter 2 of ibc. However, the definition you referenced is for (bg) Area Building. Is there another location in definitions that i’m not seeing for gross? Because if not, you only referenced one portion of the definition if I’m not mistaken. It continues to state something weird “Areas of the building not provided with surrounding walls shall be included in the building area within the horizontal projection of the roof or the floor above.” This implies that if you stack balconies they are included in the gross, and if shafts run up to an enclosed AHU then the shafts would also be included, and that if your building has an overhang so would that apply? Is this correct? Please help!!
When calculating gross floor area for office, are the accessory assembly spaces (conference and break area) subtracted from the gross number or are they added? Example 3,000 sf office space, with 600 sf conference room. (3000/150 + 600/15)= 20+40 = 60 or (2400/150 + 600/15) = 16+40 = 55? Also, have you used areas of concentrated business use in one area of the floor and the normal 150 OLF in another area on the same floor? I have an “IT” department with heavy density and an executive/admin area splitting the floor.
I have a question: let’s say you have a row of private offices. Since they are have the same function, and have a GROSS occupancy factor, would you calculate each space individually or as one space? The gross definition says you can’t exclude interior wall thicknesses, but does that apply where there are walls separating a room? Would you instead calculate all the offices as one space or calculate them individually? If individually, do you figure out the square footage from the face of the wall or the center of the wall? I’ve seen it done both ways, so I want more opinions on this.
Super helpful! Can a article be made clarifying egress convergence and how occupant load and egress requirements are calculated for each floor that is affected? So for example basement and second floor (and up) occupants all exiting through the ground floor when there are also occupants on the ground floor? Thanks!
Thank you for explaining the difference between net and gross in a clear manner! In the last part of the article (when you mentioned why bother differentiating between the two), I had that pondering thought for the longest time. Now I pose to you if calculating net could be helpful in some instances to shed square footage, then why don’t we calculate the net area for everything instead of gross? I don’t see what calculating the gross area does.
As an American Firefighter, I really find this amusing. He really hits allot of the general hot topics related to occupancy regulations.. Another really bad fire that inspired changes in fire prevention, is the station night club fire. You can look up articles and studies from that fire on YouTube, very sad, and very well studied.
The Coconut Grove fire also had anouther problem with the doors, in that the main entrance was a revolving door. People piled up in both directions on the door and jammed it. Other doors had be bolted shut to stop people from leaving without paying. Later revolving doors would be required either to be flanked by at least one outward opening non revolving door as you can probably find with any revolving door today, or on older examples, retrofitted so the leaves of the door fold flat if a panic situation was to occur.
It’s really weird that you’re using IBC 2009. The IBC is updated every 3 years, so the current code is IBC 2015, and IBC 2018 is going to be released in a couple months. I’m not aware of any recent changes to the occupancy calculations, but it still seems weird that you wouldn’t use the most current code.
Architect here: there is one more way of determining the occupancy that is pretty critical and usually the prevailing logic on many assembly projects: the planning department may arbitrarily set the occupancy of a space regardless of use. For example many jurisdictions will only measure “standing room” area a 1 occupant per 10sf and only use the 7sf standard if they wish to boost the occupancy up. In most cases the plan checker or the department managing staff may look at a proposal and say “don’t exceed X occupancy” regardless of how many doors you provide. Furthermore they can just say “regardless of the standard area calculations we deem the occupancy to be Y, sort it out with the fire department”
In light of the recent opiates/opioid article you did, I still think you really owe as a article about the unintentional victims of the fight against the so-called opiate crisis. Unless someone is a chronic pain patient or close to someone who is, they are unlikely to have any idea about it and we need to be included in the dialogue. I think it would interest people to see the other side, and understand why this is not as simple as making the medications rarely used. It might blow people’s minds to hear that most criteria professionals like to use to designate someone a “drug seeker” are actually entirely normal behaviors of people in serious physical pain. Or that the percentage of chronic pain patients treated with them that go on to develope a problem is quite low. Or that the “guidelines” being put forth are called voluntary but doctors are being bullied into following them and having rx numbers arbitrarily limited without any regard to how many patients actually legitimately need them, forcing many to be cut off of a working treatment they have used for years, in some cases decades. Anyway, thanks for your work, love your articles/site for years already. In general your team does excellent research and that’s appreciated. Teach the world. <3
Bonus Fact: The inferno at the Cocoanut Grove was additionally marked by extremely toxic fumes released by the decor as it burned, actually extinguishing itself in short order by depleting the oxygen it needed. Firemen and rescuers found dozens of patrons still sitting upright on barstools and presumed they were simply too drunk to have noticed the fire only to find that the combination of heat, toxins, and asphyxiation caused them to rigor almost instantly. Extra Bonus Fact: The catastrophe was so devastating to the community that the city passed a rather unique ordinance, forever banning any bar and/or nightclub from operating under the name “Cocoanut Grove”.
0.X inches? That makes no sense to me. How much X to 1 inch? 9? 10? 70(as google suggests)? How do I figure that out expressed as a fraction of an inch (what I’m actually used to using)? Also fire exits tend to have wider doorways. And is this square inches or inches just horizontally or vertically? Cubic inches even (since doorways have significant depth)? Unobstructed floor space per person seem a lot easier to figure on.
So the Truman conference was Just a show. Since worse happened before hand even with legal measures in place. Moral of the story? Find out the occupancy before staying somewhere or using somewhere during busy times. This is whybi don’t go any where in Dublin Ireland on the weekend. “It’s jammers” being an acceptable explanation do literally being crushed.
According to a punny rumor, when the first jai-alai fronton was built in Miami, the builders had planned to have only one door into and out of the playing floor downstairs, while the spectators had a dozen doors for entering and leaving. But the fire marshal said there must be at least two doors for the players. In other words, … Don’t put all your Basques in one exit!
…Or they just make random guesses as to occupancy number. twice in my life I have seen occupancy of a room be decided upon – An official coming in to put up the sign (not just a worker putting up a sign). Both times the official changed the number because of negotiation/suggestions by people in the room at the time (noone official or anything, just people using the room at the time) So I have no trust in those occupancy numbers.
Not to speak ill of the dead, but the building fire where many died to due the doors opening inward – who were the jackasses that got to the door, started pressing on it to try to open it, and then continued to try and press on it even while a surge of people surely told them to back up because it only opened one way?